The present invention pertains to a multi-positional switch for the controls of an aircraft, and, more particularly, pertains to a multi-positional electrical switch for providing tactile feedback to the operator of the various switch positions.
Switches, such as push button and toggle switches, are found in everything from cameras and computer keyboards, power tools and home appliances, automotive vehicles and industrial machinery. For the above uses, as well as numerous other uses, the operator has the opportunity and time to visually observe the position of the various operational and control switches at any moment in order to confirm the particular state, engaged or disengaged, of the switch, and to obtain assurance in the form of immediate visual feedback that the switch or switches are in their proper position.
However, in certain work environments it may not be possible or desirable for the user or operator to carefully view and inspect the particular position of the switch due to safety and operational requirements. One example of such a work environment is in the operation and control of aircraft where the pilot, co-pilot or navigator must maintain constant vigilance in order to avoid even the slightest distraction that could lead to a fatal error and a devastating accident. Many of the switches used in aircraft are multi-contact switches wherein accuracy and stability are prerequisites for proper functioning in order for the operator to easily and accurately determine the state the particular switch is in.
In general a five-way switch is utilized as the conventional type of switch for aircraft. Such conventional five-way switches are configured to allow the operator to instantly sense and perceive the act and condition of switching through the perception of sounds produced by the switch contacts. However, an acute drawback in the perception of such sounds at the actual moment of switching is that the intense noise in the cockpit, combined with the fact that the operators are often wearing headsets, thoroughly obstructs the distinct perception of the switching sounds. Therefore, it is necessary for the flight operators to reliably sense the individual switching states solely through the tactile sense.
Thus, a number of switches have been conceived for providing a tactile and/or audible sense or feeling to the operator or user of the equipment. The Harris patent (U.S. Pat. No. 4,466,302), the Wu et al. patent (U.S. Pat. No. 4,939,327), and the Skulic patent (U.S. Pat. No. 5,057,657) all disclose keyboard switches. Harris discloses a switch actuation mechanism utilizing a stem for contacting cammed surfaces that in turn engage a rocking plate member for initiating electrical energization while Wu et al. utilizes a reciprocable plunger that actuates a leaf spring and an actuating arm for producing a tactile sense and Skulic discloses a switch actuator mechanism utilizing a cooperating plunger and slide member to create the tactile sense or feeling.
The Naimer patent (U.S. Pat. No. 3,539,736) discloses a switch having a reciprocable shaft with cam elements adjoined thereto, and the cam elements actuating independently shiftable armatures.
The Roeser patent (U.S. Pat. No. 3,772,484) discloses a dual action electrical switch wherein an actuator engages a pair of pivotally mounted switch levers for engaging the dual action switch.
The Metzler patent (U.S. Pat. No. 5,907,138) discloses a push-button switch having a reciprocable rod that successively engages spring biased stops each of which corresponds to an electrical contact for initiating electrical conduction.
The Hoskins patent (U.S. Pat. No. 5,945,647) discloses an electrical control apparatus having a control member that can establish an electrical circuit by either rotary or axial motion.
Nonetheless, despite the ingenuity of the above devices, there remains a need for a multi-positional switch that provides reliable, accurate, and immediate tactile feedback to the operator regarding the various switch positions to which the switch has been shifted or toggled.
The present invention comprehends a multi-positional electrical switch for use in aircraft in order to provide an immediate tactile sensation and tactile feedback to the operator regarding the various switching positions to which the switch has been moved.
The present invention includes a generally cylindrical housing having a manually displaceable push button mounted at the upper end of the housing. Projecting out of the lower end of the housing can be one or more radially disposed terminals and a central terminal. In addition, auxiliary contacts are adjoined to the terminals, and each auxiliary contact includes a bent portion adjacent a drive stem when the drive stem is in a non-actuated state. Secured to the push button and located at the upper end of the housing therein is a deformable cap. A guide shaft is axially mounted to the cap and includes a bore for receiving therein the drive stem that can be actuated for linear, slidable reciprocable movement and radial motion within the housing by operation of the push button. A pair of sleeves is disposed within the housing for delimiting the range of axial and radial motions of the guide shaft and drive stem. An L-shaped common terminal member is disposed adjacent the lower end of the housing and includes a rectilinear portion extending outwardly from the end of the housing and a circular portion disposed within the housing and below the guide shaft. The circular portion includes an aperture through which the drive stem can extend. Confined between an interior flange of the guide shaft and the circular portion of the common terminal member is a compression spring.
Closing off the lower end of the housing is a lower enclosure plate, and the lower enclosure plate supports the central terminal. The central terminal protrudes outwardly from the lower enclosure plate and is in general axial alignment with the drive stem when the push button is in the non-operational state. Disposed within the housing and supported on the lower enclosure plate is a toggle or shifting plate. The toggle plate also has an aperture through which the drive stem can extend when the push button is actuated. Located immediately below the toggle plate is a spring-mounted resistance pin for offering resistance to the drive stem as the drive stem passes through the aperture of the toggle plate for contacting the central terminal.
By manipulating the push button the operator can move the drive stem against the toggle plate in a radial direction so that the drive stem contacts the auxiliary contacts for electrical energization and switching. When the operator applies a downward force in the axial direction, the drive stem is forced through the aperture of the toggle plate contacting and overcoming the resistance of the resistance pin, which the operator perceives by through the tactile sense alone. Further downward pressure by the operator""s finger applied to the push button causes the drive stem to contact the central terminal.
It is an objective of the present invention to provide a multi-positional switch that provides an easy and immediate perception to the operator of the particular switching state of the switch through tactile sensation alone.
It is another objective of the present invention to provide a multi-positional switch which can be moved and toggled in both axial and radial directions and which conveys the tactile sense to the operator when external pressure exceeds a predetermined limit is applied to the switch.
These and other objects, features, and advantages will become apparent to one skilled in the art upon a perusal of the following detailed description and accompanying drawings.